I'm aware of Wii has them Wii64, Not64 or DeSmuMe so figure why not try work on Wii U Homebrew so it would be Wii64 U or DeSmuMe U. Thank you for read this and please free to write comments
For N64, there's no need for specific emulators when you can either use N64 VC injects on Loadiine or USB Install or overclock the existing Wii64, so it's far better than just using the regular laggy version.
In terms of DS, you can just do the same like I said for N64, use VC Injects on Loadiine or USB Install.
Except N64 is not as Compatible it needs more Work but myself and a bunch of others im sure are working on it , would really complete the Wii U AIO Experience.
It Plays Every other Nintendo except 3DS , Switch.